The present invention, in some embodiments thereof, relates to oscillatory vorticity generation on aero- or hydrodynamic surfaces and, more particularly, but not exclusively, to oscillatory vorticity generation at airfoils such as on aircraft wings or wind turbine blades.
Several methods are known in the art for actively manipulating fluid flow over a surface. One method widely used employs active flow control to increase turbulence, and more specifically certain relevant scales of turbulence, on the aerodynamic surfaces, for example by use of synthetic jet actuators.
US 2007/0095987 to Glezer et al. discloses a synthetic jet actuator including a jet housing that incorporates an internal chamber with a volume of fluid and a small orifice in one dimension of the chamber connecting the internal chamber to an external environment having the fluid to be controlled. The synthetic jet actuator disclosed is operative to periodically change the volume within the internal chamber such that a synthetic jet stream entrained by a series of fluid vortices is generated and projected to the external environment.
US 2007/152104 to Cueman et al., for example discloses an array of synthetic jet actuators integrated in various applications, such as in aircraft engines or wings. Each actuator includes a chamber, a flow control port (a small orifice in one dimension of the chamber) and opposite parallel side walls configured to expand apart and contract together to flow a control fluid through the flow control port in response to an input.
US 2003/075615 to Saddoughi discloses a synthetic jet actuator disposed in a wall of a flow-path, such as an airfoil. The synthetic jet actuator consists of a rectangular cavity in the wall wherein the open side of the cavity is covered by an actuator blade such that a small orifice is left in the covered opening.
Additional background art includes WO 08/113,349 by Godsk, K. B., U.S. Pat. No. 5,758,823 to Wiltse, J. et al., U.S. Pat. No. 6,412,732 to Amitay, M. et al. and US 2006/140760 to Philippe G.